The present invention relates to the field of determining and evaluation of fatigue of a user, in particular to evaluation of fatigue of a vehicle driver and alerting the driver if the driver drifts from wakefulness to drowsiness.
The National Sleep Foundation's (NSF) 2002 Sleep in America poll shows that more than one-half of the adults in this country admit to driving while drowsy; seventeen percent say they actually fell asleep at the wheel in the past year.
The National Highway Traffic Safety Administration (NHTSA) conservatively estimates that 100,000 police-reported crashes are the direct result of driver fatigue each year, representing more than 1,550 deaths, 71,000 injuries, and $12.5 billion in economic costs. Studies show that young adults between the ages of 16 and 29 are the most likely to drive while drowsy. However, shift workers, commercial drivers, and people with untreated sleep disorders such as sleep apnea are also at higher risk.
Many physiological measures have been examined in earlier studies as predictors or indicators of driver fatigue.
An increased percentage of eyelid closure is one of the most reliable predictors of the onset of sleep. However, a camera and demanding eye-tracking software must be used to measure this percentage.
Spectral electroencephalogram (EEG) analysis is the most appropriate method for detecting the onset and different stages of sleep. But, this method is useful in laboratory settings only and in a large degree depends on the person's individual physiological factors.
The correlation between heart rate variability and fatigue is a proved fact, but it is difficult to implement in a real world environment. The change in skin potentials during the drift from alertness to drowsiness is a very challenging idea, but there are no reliable correlations still found. There are numerous methods of monitoring driver-vehicle relations as predictors of fatigue, but they are complicated and prone to false alarms.
The present invention offers an effective method and apparatus for monitoring the fatigue level of a driver and alerting the driver, or others, if the driver drifts to a predetermined state of drowsiness.